Radio communication terminal and gain control circuit for the same

Abstract

A gain control circuit has a transmission power amplifier that amplifies a transmission signal to a predetermined level. An adjacent channel leak power ratio monitor finds a ratio of a distortion element corresponding to an adjacent channel leak power to a main element from an output signal supplied from the transmission power amplifier, and outputs the found ratio as an ACPR monitor value. A power supply control section variously controls power supply to the transmission power amplifier with use of the ACPR monitor value supplied from the adjacent channel leak power ratio monitor. A transmission signal level variable section controls a gain of a transmission signal path on the basis of a transmission level monitor value supplied from the adjacent channel leak power ratio monitor, thereby varying a level of the transmission signal.

1. A gain control circuit, comprising:
 a transmission power amplifier which amplifies a transmission signal to a predetermined level; 
 an adjacent channel leak power ratio monitor which finds a ratio of a distortion element corresponding to adjacent channel leak power to a main element from an output signal of the transmission power amplifier, and outputs the found ratio as an ACPR monitor value; 
 a power supply control section which variably controls power supply to the transmission power amplifier with use of the ACPR monitor value supplied from the adjacent channel leak power ratio monitor; 
 a transmission signal level variable section which varies a level of the transmission signal by controlling a gain of a transmission signal path on the basis of a transmission level monitor value supplied from the adjacent channel leak power ratio monitor; and 
 wherein the adjacent channel leak power ratio monitor comprises: a squaring circuit which squares an output signal of the transmission power amplifier; a first band path filter which extracts a distortion element corresponding to the adjacent channel leak power from an output signal of the squaring circuit; a second band path filter which extracts an element corresponding to a main part of the output signal of the squaring circuit; and a subtracter which performs a subtraction process between an output of the first band path filter and an output of the second band path filter. 
 
     
     
       2. The circuit according to  claim 1 , wherein the squaring circuit includes a multi-plier which multiplies at least two signals together. 
     
     
       3. The circuit according to  claim 1 , wherein the squaring circuit includes a non-linear device having a second-order distortion coefficient. 
     
     
       4. A radio communication terminal comprising a radio transmission section, wherein
 the radio transmission section comprising: 
 a transmission power amplifier which amplifies a transmission signal to a predetermined level; 
 an adjacent channel leak power ratio monitor which finds a ratio of a distortion element corresponding to adjacent channel leak power to a main element from an output signal of the transmission power amplifier, and outputs the found ratio as an ACPR monitor value; 
 a power supply control section which variably controls power supply to the transmission power amplifier with use of the ACPR monitor value supplied the adjacent channel leak power ratio monitor; 
 a transmission signal level variable section which varies a level of the transmission signal by controlling a gain of a transmission signal path on the basis of a transmission level monitor value supplied from the adjacent channel leak power ratio monitor; and 
 wherein the adjacent channel leak power ratio monitor comprises: a squaring circuit which squares an output signal of the transmission power amplifier; a first band path filter which extracts a distortion element corresponding to the adjacent channel leak power from an output signal of the squaring circuit; a second band path filter which extracts an element corresponding to a main part of the output signal of the squaring circuit; and a subtracter which performs a subtraction process between an output of the first band path filter and an output of the second band path filter. 
 
     
     
       5. The radio communication terminal according to  claim 4 , wherein the squaring circuit includes a multi-plier which multiplies at least two signals together. 
     
     
       6. The radio communication terminal according to  claim 4 , wherein the squaring circuit includes a non-linear device having a second-order distortion coefficient.